Personal video recording functions allow a user to rewind, fast forward, pause, and play video data in slow motion. The foregoing functions can be implemented by displaying selected pictures from the pictures forming the video data.
Many video compression standards introduce data dependencies between pictures in a video. As a result, some pictures in the video are data dependent on other pictures in the video. Pictures that are data dependent on other pictures are decoded after the other pictures.
The compression standards typically restrict the permissible data dependencies between pictures in the video data, such that the decoding order has some relationship to the standard video display order. However, the decoding order can be vastly different from the rewind and fast forward order.
Due to copyright and security concerns, video data is increasingly encrypted. The video data is usually transmitted in transport packets. The transport packets include a header and payload. The payload includes encrypted video data.
The use of encrypted data complicates personal video recording functions. Certain personal video recording functions can display pictures in a different order from the standard playback order. In standard playback, the video data stream is accessed and consumed in generally a continuous manner. During a number of personal video recording functions, the video data is displayed in a non-continuous order. The encryption complicates accessing the video data at the appropriate intervals.
Further limitations and disadvantages of conventional and traditional systems will become apparent to one of skill in the art through comparison of such systems with the invention as set forth in the remainder of the present application with reference to the drawings.